Do NOT use the same hose to fill your water tanks!
In fact, I don't really recommend your method at all, Terry. 60 pounds of water pressure down a narrow hose can produce some surprising and unpleasant results. Follow these directions for maintaining your vent, and it shouldn't be necessary:A tank cannot be emptied under vacuum. Unless air can be pulled in through the vent to replace the waste (or anything else in ANY container) being pulled out, a vacuum is created in which nothing more can beremoved--but in which the suction CAN crack the tank. A blocked vent also prevents the air displaced by incoming contents from escaping, which results in a pressurized tank. This can have disastrous consequences--anything from blown out fittings to a cracked tank to a sewage geyser when the pumpout fitting cap is removed to a backup in the toilet. Follow these "rules" to prevent the above problems: 1. check your vent through-hull regularly...blast it out with a hose every time you wash the boat;2. Never turn pumpout operation over to a dockhand and walk away. Stay there and watch to make certain that the tank is being completely pumped out. Terminate pumpout/dumping at sea immediately if waste stops flowing before the tank is empty. Do not try to pump out or dump the tank again until the vent has been cleared.3 Stop flushing and cease using the toilet when you feel any backpressure or see any waste backing up into the toilet.4. The vent is NOT an overflow. Only air should ever pass through it. Accidents do happen, though, and they can result in a clogged vent. Cease using the toilet immediately if you see waste coming out the vent and and get to a pumpout as soon as possible so that waste doesn't have time to dry and harden in the vent hose. Flush it out VERY thoroughly with clean water to remove any bits of waste in it. To prevent overflows out the vent, install a gauge.